Circular kiln



June 26, 319280 T. C. FROUTY ET AL CIRCULAR KILN 4 Sheets-Sheet 1' MWM I l-e rmy lw i o 7 I" a Y ,w 5% m T. c. PROUTY ET AL CIRCULAR KILN Original Filed March 7, 1925 4 Sheets-Sheet 2 I //1 Men 101;;

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T. C. PROUTY ET AL CIRCULAR KILN Original Filed March 7, 1925 4 Sheets-Sheet 4 N I I. 1:. m wmu/ A1] E m J 5M 4 f v 4 p -WIIN A/ U V H/ Patented June 26, 1928.

UNITED STATES 1,674,992 PATENT OFFICE.

THEODORE C. PROUTY AND WILLIS O. PROUTY, OF HERMOSA BEACH, CALIFORNIA, AS- SIGNORS. BY MESN E ASSIGNMENTS, TO AMERICAN ENCAUSTIC TILING COMPANY, LTD, 013 LOS ANGELES, CALIFORNIA, A CORPORATION OF NEW YORK.

CIRCULAR KILN.

Application filed March 7, 1925, Serial No. 13,885. Renewed May 16, 1928.

Our invention consists in a kiln of improved form for firing ceramic products, and designed to secure economy and ease and certainty of control in operation. 'Ourimproved kiln is of the tunnel type, but is 011'- cular in form. These kilns as generally constructed' have taken the form of a straight tunnel through which a line of separate cars carrying the charge is moved, the cars being 0 removed from the discharge end of the kiln,

unloaded, loaded with a new charge and returned tothe charging end of the kiln. In our improved kiln we construct the tunnel in the form of a complete circle provided with a single opening for charging and discharging the ware. 1n place of the separate cars heretofore used for carrying the charge through the kiln we provide our circular kiln with a continuous circular carriage ex- 2 tending as a unitary structure completely around the circumference of the kiln. Bea-ring rails fixed rigidly to and forming part of the under side of the carriage rest upon anti-friction wheels mounted in stationary bearing; in the bottom of the tunnel. Sand seals between the Walls of the tunnel and the carriage separate the lower part of the tunnel containing the anti-friction rollers from the upper heated zone through which the charge is carried. A kiln of this type may be constructed of any desired dimensions, for any desired method of use and with various ways of applying heat.

In the kiln illustrated in the accompanying drawings we have shown the opening for charging and discharging the ware diametrically opposite the zone of maximum heat and with the charge indirectly heated in the preheating zone and subjected to the direct, uninterrupted action of the source of heat in the maximum temperature zone, but the use of our circular kiln is not limited to or dependent upon these particular arrangements. have found advantage in the form and disposition of the elements shown in the drawing, and have also found that close control of temperature is facilitated by constructing the tunnel of relatively small cross-sectional area. and dispensing with the saggers usually employed for containing the charge. By placing the ware in open formation 'upon the carriage without saggers economy is effected in avoiding the cost of the saggers and the In practice, however, we.

labor of handling them and heat necessary to raise them to the necessary temperature. In operating our improved kiln we set the ware upon flat slabs of refractory material which with the material uponthem are easily transported to and from the kiln, or if desired the slabs may be permanently mounted on the carriage at one or more levels and the ware may be arranged upon them during the movement of the carriage past the char mg opening, this movement being sufficiently slow to afford ample time. In operating the furnace illustrated in the drawings the preheating which is efiected before the Ware is exposed directly to the source of heat in' the zone of maximum temperature raises the temperature of the ware sufficiently to preyent cooling of the burning gases and resulting separation of carbon, the purpose being to utilize the heating efliciency and certainty of temperature control incident to the direct application of heat as soon as the ware has by indirect heatingbee-n raised to a temperature sufliciently high to avoid separation and deposit of carbon.

In the drawin s:

Figure 1 is a orizontal section.

Figure 2 is a vertical section on line BB of Fig. 1. i

F igure 3 is a vertical sectional view, the part to the left of the center line being on the line FF of Fig. 1 and the part'to the right of the center line being on line N'-N ofFig. 1.

Figure 4; is a Vertical section on line SS of Fig. 1. I

Figure 5 is a fragmentary horizontal section on the line LL of Fig. 2 showing the lower part of the maximum heat zone or high heat chamber of the kiln.

Figure 6 is a Vertical fragmentary horizontal section on the line R-R of Fig. 3.

Figure 7 is a diagrammatic view of means suitable for rotating the circular carriage.

The continuous circular carriage, designated generally by the letter A, is rotated counter-clockwise in the kiln illustrated. It comprises a horizontal circular platform or floor 1, having at its outer edges flanges 2, 3 which take the form of continuous annular troughs containing sand. Depending continuous annular flanges 4, 5, formed on circular members attached to the inner and outer Walls of the tunnel extend into the sand in troughs 2, 3, and form continuthe space below the floor 1 of the carriage from the space above. The frame of the carriage com rises the floor 1 and two continuous circu ar members, 6, 7, depending from and rigidly attached to the floor. The members 6, 7 are each provided with a circular series of openings to receive the tie bars or spokes 8 the openings being so spaced that each spoke-takes a radial position. The spokes are held in position and the entire structure of the carriage is heldin circular form by nuts, 9, threaded upon the spokes and clamping the members 6, 7. The edges of the members 6, 7, rest upon the flanged bearing wheels 10, 11 mounted upon axles 12 journaled in the uprights 13 of the pedestals 14. There is a circular series of these pairs of bearing wheels placed at suitable intervals around the floor of the tunnel. Power for driving the carriage may be applied in any convenient way. A. method we have employed is shown diagrammatically in Figure 7 in which 15 designates a chain extending around the circumference of the carriage and engaging pins 16 projecting therefrom. Chain 15 engages a toothed drive wheel 17 which may be rotated at the desired speed through gearing driven from any suitable source of power. Upon the upper side of the carriage We have shown a series of partitions 18 each substantially filling the cross section of the tunnel. The precise number of these parti tions is not a critical matter in the operation of the kiln after it has been raised to firing temperature. In bringing the kiln up to operating temperature before it has been charged with ware, however, the partitions serve an important purpose in checking the flow of heated gases through the tunnel and after the kiln has been raised to operating temperature and charged more efficient operation is secured by the presence of several of the partitions. Preferably we make the distance between the partitionsequal to the width of each of the direct heat firing chambers 19, 20.

The charging and discharge opening of the tunnel is indicated 0. Figure 1, and from that point to the direct heat chambers 19, 20 the cross section of the tunnel opening is just sufficient to receive the carriage and the ware upon it, the clearance around the carriage and the loading space thereon being merely that necessary for practical operation. This is the preheating part of the kiln, and in this zone the sources of heat are separated from the ware by the walls of the ducts in the sides and top of the tunnel into which the burning gases are delivered. We have shown four pre-heating burners 21, 22, 23 and 24 in the outer Wall of the tunnel and three burners, 25, 26, and

evaeea 27, in the inside wall. Either gas, oil or solid fuel may be used and in referring to burners we include any suitable source of heat. All of these burners 21 to 27 are similarly arranged with reference to the conveyance of heat to the ware being fired. The position of the burner 21 is shown in Figures 1 and 3 and in Figure 6 we have shown the disposition of the staggered flue through which the products of combustion of burner 21 flow. The flame and products of combustion of burner 21 pass through the radial duct 28, the inner end of which communicates with the baflled or staggered duct 29, 30, 31, 32, 33, 34 and 35, which is separated from the interior firing compartment of the tunnel by the thin wall 36. We have indicated the course of flow of gases by arrows in Figure 6. From the upper reach 35 of the staggered passage the gases escape through spaces 39 between blocks 40 to the space 37 above the roof 38 of the firing compartment. All of the burners 21 to 27 are arranged in the same way and all communicate with the space 37 which extends over the part of-the firing compartment opposite the burners 21 to 27 but stops just short of and does not communicate With the direct firing chambers 19, 20. The gases flow through flue 37 from the burners toward the chimneys 41, 42, with which the flue 37 communicates as indicated at the right of Figure 3 where the space 37 is shown opening into chimney 42.

Extending from chimneys 41, 42 toward the charging and discharge opening C are flues 43, 44 adjacent the side walls of the firing compartment and opening at their outlet ends into the branches D D of the stack D as shown in Figure 4. The branches D D of the stack extend downward on the opposite sides of the firing compartment to a junction with the side flues 43, 44. The products of combustion escape to the atmosphere through stack D. No heat is applied to the firing compartment between stack D and the charging and discharge opening C. Between chimneys 41, 42 and stack D the firing compartment receives heat only from the side flues 43 and 44 through which the gases pass after having given up most of their heat. In the part of the pre-heating zone between the direct heating chambers 19, 20 and the chimneys 41, 42 heat is communicated to the firing compartment from the burners 21 to 27 through the thin walls 36 of the sets of staggered ducts 29-35 with which the burners communicate and through the roof 38 above which the gases from the burners pass to the chimneys 41,42. As shown in Figure 1 the exterior part of the walls of the tunnel in the zone occupied by the burners 21 to 27 is relatively thick to retain the heat, but are thinner between the chimneys 41, 42 and the stack D to permit suificient radiation of heat to provide a gradual and even rise in temperature inward from the charging opening. Between the stack 1.) and the charging opening we have shown the tunnel walls not only relatively thin but also provided with fins to increase the radiation of heat and bring the temperature down to the proper-point for the entrance of the ware into the kiln.

In the direct firing chambers 19, 20 the ware is exposed to direct contact with the products of combustion. of this part of the kiln is shown in Figures 1, 2 and 5, Figure 2 being a section through the kiln on the line 13-15 at the center of chamber 19. Chambers 19 and 20 are snnilar in their general arrangement, but reversely arranged with respect to the circular carriage, the parts upon the inner and outer sides of the carriage in chamber 19 being respectively upon the outer and inner sides in chamber 20. Projecting from the outer and inner vertical walls 45, 46 of chamber 19 are horizontal shelves 47, 48. Openings 49, 50 are provided for burners 51, 52, 53 and 62. The flame and gases impinge upon vertical baflles 54, which project upwardly from the 'outer edges of shelves 47, 48. Preferably we place two burners 51, 52 above shelf 47 and a single burner 53 above shelf 48 and carry the battle 55 some what higher than the battle 54. Bafie-55 extends completely across shelf 47 while we have shown baffle 54 as occupying only the central part of the edge of shelf 48, thus permitting the gaseous products of burnerv 53 to pass around the ends as well as over the top of baffle 54. The shelf 48 does not project into chamber 19 as far as shelf 47 thus leaving space between the edge of shelf 48 and the carriage for the downward passage of the gases. Beneath the shelves 47 and 48 and between them and the floor 56 of the chamber is a transverse duct 57 extending through the outer wall of the kiln to the carriage compartment andinto the inner wall to a point over the circumferential flue 58. Extending completely around the carriage is a series of transverse ducts 59 separated only by relatively thin vertical walls 60 which extend radially of the kiln struc- 'ture. The ducts 59 may conveniently be constructed of refractory brick or plates supported upon brick-work 61 built up on the floor of the carriage. As the carriage revolves the ducts 59 successively come into registry withthe duct 57 thus, except for the negligible obstruction of the vertical side walls 60, maintaining constant communication through the duct 57 to the circumferential flue 58. The flame and gases from a burner 62 at the outer end of duct 57 are projected through the ducts 59 carried by the carriage and pass thence to flue 58, a

The constructionform and function with flue 58'.

part of the gases finding their way upward and through the ware carried onthe upper horizontal surface 68 of the structure forming the ducts 59. The cross-sectional area of the charge will be of practically the same in outline as that of the partition 18 shown in Figure 2 and other views.

As above stated the arrangement of the burners and other parts in chamber 20 is similar to that in chamber 19, but reversely arranged with respect. to the carriage and delivering the gaseous products of combust-ion into a flue 58? which corresponds in The only difference in the form of construction is in placing the baflle 65 and burner 66 of chamber 20, corresponding to baffle 54 and burner 53 of chamber 19 at one side with the baffle 65 projecting from the side wall, and a short bafiie plate 64 projecting inwardly from the outside Wall at the side of the burner. The purpose of this arrangement is to deflect the flame and gases from burner 66 away from the cooling zone, which extends from chamber 20 to the discharge and charging opening C, one of the objects of our invention being to bring about an abrupt fall in the temperature of the ware immediately upon its leaving the zone of maximum heat within the chambers 19, 20. temperature is accelerated by the thinness of the walls of the tunnel from a point just beyond chamber 20 to opening G, and by the provision on this part of the walls of fins 65 to assist in the radiation of heat.

' Flues 58 and 58 extend at the level shown in Figure 2 circumferentially of the kiln .to the chimneys 42, 41 respectlvely. Flue 58 appears in the section at the left of Figure 3, this being a section intermediate the ends of the flues 58, 58', and in the section at the right. of Figure 3 we have indicated in dotted lines the junction of flue 58 with chimney 42 and the flow of gases therefrom is indicated by dotted arrows. We have indicated the position of flue 58 in dotted lines as it enters flue 42 from the side toward the observer of the drawing and would not therefore appear in this section which shows the half of the chimney opposite the side where flue 58 enters it. The gases from flues 58 and 58' join the gas es from the preheater burners 21 to 27 in the side flues 43, 44 and pass with them to the stack D.

We claim:

1. In a furnace of the class described a muflie, means for moving material therethrough, independently controllable sources of heat coacting with separate successive sections of the walls of said muffle.

2. In a furnace of the class described a muflle, means for moving material therethrough, a plurality of independently-controllable sources of heat, a plurality of flues communicating respectively with sand sources This abrupt fall in of heat, said flues lying contiguous to and being adapted to impart heat to successive sections of the walls of said niuflie.

3. A furnace of the class described comprising means for conveying material therethrough,- a mufile extending through part only of the length of said furnace and surrounding the space provided for the material borne by said conveying means, means for imparting heat to said material through the walls of said mufil'e, and means for imparting heat directly to said material when in the part of said furnace not occupied by said mufile.

4. A furnace of the class described comprising means for conveying material therethrough, a plurality of independently controllable burners for imparting heat to the material borne by said conveyor, a wall surrounding part of the path of movement of said material and intervening between said material and certain of said burners, and others of said burners having direct access to and projecting the products of combustion into the space through which the material is conveyed.

5. A kiln comprising a circular tunnel comprising preheating, high-heat and cool ing zones, and exteriorly projectlng heat radiating fins on the outside of the cooling zone section of said kiln.

6. A tunnel kiln, a conveyor therein, low heat and high heat flues in the wall of said kiln and a direct heating chamber communicating with the interior of the tunnel of said kiln, said direct heating chamber and high heat flue communicating with said low heat flue, means for supplying heated gases .of combustion to said chamber and high heat flue and means for discharging gases from said low heat flue.

7. A tunnel kiln, a conveyor therein, a plurality of independent high heat flues in the walls of said kiln, said flues having inlets to receive hot gases of combustion, and low heat flues in the wall of said kiln to receive the gases discharged from said high heat flues.

8. A tunnel kiln, a conveyor therein, a plurality of independent high heat flues in the walls of said kiln, said flues having inlets to receive hot gases of combustion, and low heat flues in the walls of said kiln to receive the gases discharged from said high heat flues, the walls of said kiln being relatively thick in the zone of said high heat flues and thinner in the zone of said low heat flues.

9. A tunnel kiln, a conveyor therein, a plurality of high heat flues in the walls of said kiln, said flues having inlets to receive hot gases of combustion, and low heat flues in the walls of said kiln to receive the gases discharged from said high heat flues, the walls of said kiln being relatively thick in the zone of said high heat flues and thinner in the zone of said low heat flues, and cooling tins projecting from the walls of'said kiln in the zone of said low heat flues.

10. A tunnel kiln, a conveyor therein, a plurality of high heat flues in the walls of said kiln, said flues having inlets to receive hot gases of combustion, and low heat flues in the walls of said kiln to receive the gases discharged from said high heat flues, the walls of said kiln being relatively thick in the zone of said high heat flues and thinner in the zone extending beyond said high heat flues in the direction of movement of said conveyor.

11. A tunnel kiln, a conveyor therein, a plurality of high heat flues in the walls of said kiln, said flues having inlets to receive hot gases of combustion, and low heat flues in the walls of said kiln to receive the gases discharged from said high heat flues, the walls of said kiln being relatively thick in the zone of said high heat flues and thinner in the cooling zone extending beyond said high heat flues in the direction of movement of said conveyor, and cooling fins pro jecting from cooling zone.

12. In a tunnel kiln, a conveyor, said conveyor comprising a platform for carrying the charge to be fired, aseries of transverse ducts extending across said conveyor beneath said platform, heating flues in the sides and top of part of said tunnel and means for projecting the gaseous products of combustion through said ducts, said means being in the part of the kiln through which said conveyor travels next after passing the part where said flues are situated.

13. In a tunnel kiln, a conveyor, said conveyor comprising a platform for carrying the charge to be fired, a series of transverse ducts extending across said'conveyor beneath said platform, heating flues in the sides and top of part of said tunnel and means for projecting the aseous products of combustion through sai ducts and into the interior of said tunnel above said platform, said means being in the part of the kiln through which said conveyor travels next after passing the part where said flues are situated.

In testimony whereof, We have subscribed our names.

the walls of said kilnin said THEODORE G. PROUTY. WILLIS O. PROU'IY. 

